In conventional practice, a variety of airtight compressors, in which compression mechanisms and drive motors or the like for driving the mechanisms are housed within airtight containers, have been used in order to compress refrigerant gas or other compression media. An example of an airtight compressor is a rotary compressor in which the compression mechanism is configured from a cylinder, a roller which rotates inside the cylinder, and a blade in slidable contact with the external periphery of the roller.
In the rotary compressor disclosed in Japanese Laid-open Patent Publication No. 6-074176, an oil reservoir is formed in the bottom of an airtight container. When the compressor is operating, the lubricant oil of the oil reservoir passes through an oil supply passage formed inside a crankshaft, and the oil is supplied to the compression mechanism interior and a bearing of the crankshaft. The oil supply passage communicates a gas retention space above the compression mechanism in which compressed refrigerant gas is temporarily retained, with a compression space inside the compression mechanism.
In this rotary compressor, a hole for expelling foamed refrigerant gas which adversely affects the supplied oil is provided to an elastic bearing groove of a main bearing. This hole is also tapered in order to avoid damage between the external periphery of the roller and the distal end of the blade.
Specifically, in the structure disclosed in Japanese Laid-open Patent Publication No. 6-074176, a hole as a second channel separate from the oil supply passage is formed through a bearing end plate and opened into the gas retention space via a discharge muffler outlet.